Added Knob Button app for Puck.js (v2)

apps.json

@@ -277,5 +277,17 @@
     "storage": [
       {"name":".bootcde","url":"app.js"}
     ]
+  },
+  { "id": "knobbutton",
+    "name": "Knob Button",
+    "icon": "icon.png",
+    "version":"0.01",
+    "description": "Use the Puck.js (v2) as an anywhere knob: push the button to transmit the angle of rotation in BLE advertising packets.",
+    "tags": "bluetooth",
+    "readme": "README.md",
+    "needsFeatures":["BLE","ACCEL"],
+    "storage": [
+      {"name":".bootcde","url":"app.js"}
+    ]
   }
 ]

apps/knobbutton/ChangeLog

@@ -0,0 +1 @@
+0.01: New App!

apps/knobbutton/README.md

@@ -0,0 +1,26 @@
+# Knob Button
+
+Use the Puck.js (v2) as an on-demand knob: rotate to the desired angle and press the button.  The angle of rotation will be advertised to any Bluetooth Low Energy receivers in range.
+
+## Usage
+
+Load the app onto the Puck.js (v2) and then:
+- hold the Puck.js in a vertical position (ex: against a wall)
+- rotate to the desired angle
+- press the button
+- observe the green LED flash
+- observe BLE advertising packets with the angle of rotation data for ~5 seconds
+
+## How it works
+
+The Puck.js (v2) will wake on button press and read the accelerometer.  The angle of rotation will be calculated based on the accelerometer's X-axis and Y-axis readings.  The value is advertised as a JSON string in a manufacturer-specific data packet using the Espruino company code (0x590), for example:
+
+    {angleOfRotation:123}
+
+[Pareto Anywhere](https://www.reelyactive.com/pareto/anywhere/) open source IoT middleware will automatically interpret these packets using its [advlib-ble-manufacturers](https://github.com/reelyactive/advlib-ble-manufacturers) library which supports Espruino advertising packets.
+
+Following a button press sequence, the Puck.js (v2) will return to low-power sleep, waking again on any subsequent button press.  It will also periodically advertise the name "Knob.js".
+
+## Adapt the code
+
+See the reelyActive's [Puck.js Development Guide](https://reelyactive.github.io/diy/puckjs-dev/) to load the source code in the Espruino IDE and adapt it to meet your needs!

apps/knobbutton/app.js

@@ -0,0 +1,103 @@
+/**
+ * Copyright reelyActive 2022-2024
+ * We believe in an open Internet of Things
+ */
+
+
+// User-configurable constants
+const LED_BLINK_MILLISECONDS = 50;
+const STABLE_ACCELERATION_TOLERANCE_G = 0.1;
+const ANGLE_ADVERTISING_DURATION_MILLISECONDS = 5000;
+const ANGLE_ADVERTISING_PERIOD_MILLISECONDS = 500;
+const NAME_ADVERTISING_PERIOD_MILLISECONDS = 5000;
+
+
+// Non-user-configurable constants
+const ACC_SAMPLE_RATE_HZ = 12.5; // Valid values are 1.6, 12.5, 26, 52, 104, 208
+const ACC_PER_G = 8192;
+const DEG_PER_RAD = 180 / Math.PI;
+
+
+// Global variables
+let advertisingTimeoutId;
+
+
+// Calculate the angle of rotation based on the given accelerometer reading
+function calculateAngleOfRotation(acc) {
+  let ratioXY = ((acc.y === 0) ? Infinity : Math.abs(acc.x / acc.y));
+  let ratioYX = ((acc.x === 0) ? Infinity : Math.abs(acc.y / acc.x));
+
+  if((acc.x >= 0) && (acc.y >= 0)) {
+    return Math.round(Math.atan(ratioYX) * DEG_PER_RAD);
+  }
+  if((acc.x <= 0) && (acc.y >= 0)) {
+    return Math.round(90 + (Math.atan(ratioXY) * DEG_PER_RAD));
+  }
+  if((acc.x <= 0) && (acc.y <= 0)) {
+    return Math.round(180 + (Math.atan(ratioYX) * DEG_PER_RAD));
+  }
+  if((acc.x >= 0) && (acc.y <= 0)) {
+    return Math.round(270 + (Math.atan(ratioXY) * DEG_PER_RAD));
+  }
+}
+
+
+// Advertise the name "Knob.js"
+function advertiseName() {
+  NRF.setAdvertising({}, {
+      showName: false,
+      manufacturer: 0x0590,
+      manufacturerData: JSON.stringify({ name: "Knob.js" }),
+      interval: NAME_ADVERTISING_PERIOD_MILLISECONDS
+  });
+}
+
+
+// Advertise the angle of rotation for a specific period
+function advertiseAngleOfRotation(angleOfRotation) {
+  if(advertisingTimeoutId) {
+    clearTimeout(advertisingTimeoutId);
+  }
+
+  NRF.setAdvertising({}, {
+      showName: false,
+      manufacturer: 0x0590,
+      manufacturerData: JSON.stringify({ angleOfRotation: angleOfRotation }),
+      interval: ANGLE_ADVERTISING_PERIOD_MILLISECONDS
+  });
+
+  advertisingTimeoutId = setTimeout(advertiseName,
+                                    ANGLE_ADVERTISING_DURATION_MILLISECONDS);
+}
+
+
+// Handle a button press: blink green LED and initiate accelerometer readings
+function handleButton() {
+  Puck.accelOn(ACC_SAMPLE_RATE_HZ);
+  LED2.write(true);
+  setTimeout(function() { LED2.write(false); }, LED_BLINK_MILLISECONDS);
+}
+
+
+// Handle accelerometer reading: terminate accelerometer readings and advertise
+//                               angle of rotation once magnitude is stable
+function handleAcceleration(data) {
+  let magnitude = Math.sqrt((data.acc.x * data.acc.x) +
+                            (data.acc.y * data.acc.y) +
+                            (data.acc.z * data.acc.z)) / ACC_PER_G;
+  let isStableMagnitude = (magnitude < 1.0 + STABLE_ACCELERATION_TOLERANCE_G) &&
+                          (magnitude > 1.0 - STABLE_ACCELERATION_TOLERANCE_G);
+
+  if(isStableMagnitude) {
+    let angleOfRotation = calculateAngleOfRotation(data.acc);
+
+    Puck.accelOff();
+    advertiseAngleOfRotation(angleOfRotation);
+  }
+}
+
+
+// Advertise "Knob.js", wake on button press and handle accelerometer readings
+advertiseName();
+Puck.on('accel', handleAcceleration);
+setWatch(handleButton, BTN, { edge: "rising", repeat: true, debounce: 50 });